Reagent strips and films are often a helpful analytical tool in the fields of clinical chemistry, analytical medicine and food sanitation diagnostics. For example, it is advantageous to determine or to test, through quantitative or qualitative methods, various matrices, including body fluids such as serum and urine, and food, such as meat products, fruit, vegetables, milk, honey and the like. Such matrices can be tested for a variety of analytes including a variety of chemicals, biochemicals and biological molecules such as bacteria, antibiotics, for example, sulfa drugs, tetracyclines, beta-lactam drugs; toxins, such as aflatoxin, zearalonone, ochratoxin, T-2, and vomitoxin, pesticides such as organophosphates and carbamates, and active metabolites, either in materials or on the surface of materials or a combination thereof.
Generally, lateral flow assays are membrane-based test devices in which a sample that is suspected of containing the analyte of interest is placed at or near one end of the membrane strip. The sample is carried to the opposite end of the membrane strip by mobile phase that traverses the membrane strip, for example by capillary action. While traversing the membrane strip, the analyte in the test sample, if any, encounters one or more reagents. The reagents can include binders for the analyte. Binders can be mobile and, therefore, flow with the sample, or be immobilized on the test strip as a capture agent. Depending on the test configuration, either the analyte binder, the analyte itself, or some other reagent in the test system will be captured by the immobilized capture agent and, thereby, produce a detectable signal. The signal can be generated by a label provided within the assay. The detectable signal can be measured, such as by an optical reader.
The presence and, in some cases, the concentration, of an analyte on a reagent strip may be determined by measuring the optical reflectance from an area of development on the strip. For example, the area of development on the strip may be an area of color development. Percent reflectance can be used to determine the result.
Testing commonly occurs in a controlled environment, such as a laboratory, but testing in non-laboratory settings is also common. In some applications speed and ease of use is particularly important. For example, in food processing it would be advantageous for tests to be run in non-laboratory settings because processors must wait for results. Further, it would also be advantageous for tests to be run on trucks during transport of the items. For that reason, it would be advantageous to accelerate the speed of testing, reduce the cost of equipment and tests, improve the ruggedness of the apparatus, and enhance the ease of use and simplicity of operation. In addition, it is advantageous to have confidence that test results are valid. Therefore, systems, methods and devices herein also assist in preventing fraudulent use of pre-run, known negative assays in place of true samples or use of assays pre-marked to provide a negative result that does not reflect the true nature of the sample. It is also desirable to increase the ruggedness of the assays, systems and test procedures.
Therefore, Applicants desire systems and methods for analyte detection without the drawbacks presented by traditional lateral flow assay systems and methods.